Field of the Invention
The present invention relates to a method for measuring a decentration and tilt of faces of an optical element and to a device for measuring a decentration and tilt of faces of an optical element.
Description of the Background Art
Position errors of optical axes of faces of an optical element generally cause aberrations, which may lead to malfunctions in an application of the element in an optical system. Such aberrations are not correctable, or often only correctable with much outlay. For these reasons, it is necessary, for example within the scope of quality control after production of the optical element, to register such position errors.
DE 10 2006 052 047 A1 has disclosed a method for determining the location of an axis of symmetry of an aspherical lens face relative to a reference axis. The method comprises the following steps:
a) determining a location of a center of curvature of a spherical component of the lens face;
b) determining an inclination of a radial profile of the lens face in a region of the lens face lying within a measurement window;
c) twisting the lens face about an axis of rotation such that another region of the lens face enters the measurement window;
d) determining the inclination of a radial profile of the lens face in the different region of the lens face;
e) repeating steps c) and d) at least twice;
f) establishing the location of the axis of symmetry of the aspherical lens face relative to the axis of rotation from the measurement values determined in steps a) and d).
Furthermore, DE 10 2006 052 047 A1 describes a device for determining the location of the axis of symmetry of an aspherical lens face relative to the reference axis. The device comprises:
a) a rotary table which is rotatable about an axis of rotation and on which a lens carrying the aspherical lens face is arrangeable,
b) a first autocollimator, the optical axis of which is aligned coaxially with the axis of rotation and the image-side focal point of which is positionable at different longitudinal positions along the optical axis thereof,
c) a second autocollimator, the optical axis of which includes an angle with the axis of rotation that differs from zero and the image-side focal point of which is positionable at different longitudinal positions along the optical axis thereof, and
d) an evaluation apparatus, which establishes the location of the axis of symmetry of the aspherical lens face relative to the axis of rotation from the measurement signals supplied by the autocollimators at different angles of rotation of the rotary table.